# A force F = (2i + 4j ) N displaces the body by s = (3j + 5k ) m in 2 sec. Power generated will be

Q: A force $\vec{F} = (2 \hat{i} + 4 \hat{j} )$ N displaces the body by $\vec{s} = ( 3 \hat{j} + 5 \hat{k} )$ m in 2 sec. Power generated will be

(a) 11 watt

(b) 6 watt

(c)22 watt

(d) 12 watt

Sol: Power , $\displaystyle P = \vec{F}.\vec{v}$
$\displaystyle \vec{v} = \frac{\vec{s}}{t}$
$\displaystyle \vec{v} = \frac{3}{2} \hat{j} + \frac{5}{2} \hat{k}$
$\displaystyle P = (2 \hat{i} + 4 \hat{j} ) . (\frac{3}{2} \hat{j} + \frac{5}{2} \hat{k} )$